This invention relates to a flush type sprinkler head adapted to be installed in a building ceiling for fire protection, and having a deflector which is housed in the main body of the sprinkler head and adapted to drop out of the main body to uniformly distribute fire extinguishing agents sprayed from the sprinkler head in case of a fire.
Of late, skyscrapers have been in most cases built with low ceilings storeys in order to increase the number of storeys in each skyscraper. Thus, a sprinkler head to be installed in the low ceiling should protrude out of the ceiling surface as little as possible. The reason is that if the sprinkler head protrudes substantially out of the ceiling surface, the sprinkler head is liable to be hit and as a result, the fire extinguishing agent is untimely sprayed (which is called as "spontaneous discharge" in the art) even when no fire breaks out in the environment where the sprinkler head is installed. A substatial protrusion of the sprinkler head out of the ceiling surface is also aesthetically undesirable.
Therefore, the sprinkler head of the flush type which can be embedded in the ceiling is suitable for the low ceiling.
The flush type sprinkler head normally houses the deflector within the main body and when it senses a fire occurring in the area of the sprinkler head, the deflector drops out of the main body by a predetermined distance so that the fire extinguishing liquid is caused to impinge against the dropped deflector which then distributes the liquid in all directions. Thus, during the operation of the sprinkler head, the deflector should be positioned in a lowered position sufficient to ensure a stabilized spraying condition for the fire extinguishing liquid or in a position spaced from the ceiling surface by at least a distance. For this reason, the installation position of the sprinkler head in the ceiling is selected taking the dropped position of the deflector into consideration.
In order to allow the deflector to drop by a greater distance from the ceiling surface, it may be contemplated that the sprinkler head is embedded in the ceiling in a shallow depth with a substantial portion of the head projecting out of the ceiling surface. However, when a substantial portion of the sprinkler head projects out of the ceiling surface, the sprinkler head is liable to be hit as mentioned hereinabove and undesirable with respect to aesthetic point of view.
In order to install the flush type sprinkler head with only a small portion thereof projecting out of the ceiling surface so as to increase the downward movement distance of the deflector, the slidable members associated with the deflector of the slide bars secured to the deflector may be increased in their length. However, the long slidable members essentially necessitates increasing the length of the main body. However, the sprinkler head having the long main body has to be embedded in the ceiling in an increased depth to cause a substantial portion of the main body to project out of the back side of the ceiling which causes a problem in the installation of the piping in the ceiling. In short, since the sprinkler head is threadably engaged with the piping on the back side of the ceiling and the piping should be firmly secured to the ceiling back side against swinging and/or dangling, the portion of the sprinkler head projecting out of the ceiling back side interferes with the securing of the piping to the ceiling.
Thus, it is desirable to provide a flush type sprinkler head which projects out of both the opposite sides of the ceiling by a small distance and provides a long downward movement distance of the deflector, but unfortunately, such a flush type sprinkler head has not been provided so far. Under the circumstances, the art has been compelled to use the flush type sprinkler head which projects out of the surface or back side of the ceiling by a substantial distance though such a flush type sprinkler head has its inherent drawbacks.
And when the prior art flush type sprinkler head is installed in an inclined location such as the ceiling over a stairway or escalator, if no water pressure is applied to the sprinkler head under particular abnormal conditions, the deflector of the sprinkler head at times does not drop properly resulting in uneven spray of the fire extingushing liquid by the sprinkler head. The cause of such uneven spray is that since the deflector of the sprinkler head is designed to drop by its own gravity along the wall surface and/or nozzle of the sprinkler head, the deflector of the sprinkler head installed in the inclined ceiling does not drop vertically with respect to the main body of the sprinkler head, but tilts under its own gravity and ceases its downward movement half-way while maintaining the tilted position.